1. Field of the Invention
The present invention relates to treating wastewater. More particularly, the invention relates to treating wastewater using a hydrodynamic cavitation system.
2. Brief Description of the Related Art
Primary objectives in the wastewater treatment industry include improving the influent quality, improving the treated effluent quality, complying with effluent limitations, and seeking more effective and efficient treatment, notably in the removal of inorganic constituents. The majority of these objectives are being met; however, a byproduct of these efforts has been the increased generation of solids and biological contaminants. In many cases, the increase in solids production has severely challenged existing solids processing and disposal methods.
Wastewater treatment facilities are well known in the art. The basic function of a wastewater treatment facility is to treat contaminated water (e.g., raw wastewater) to produce water that may be potable and/or discharged to lakes, rivers and streams. Challenges for wastewater treatment facilities include disposal of solids (e.g., sludge and/or biosolids) and/or removal of contaminants from the wastewater. Increased production of sewage, environmental impacts, and regulations regarding disposal of the sewage have made the disposal of solids and/or removal of contaminants from the wastewater more challenging.
Solids may include a significant amount of water that increases the cost of disposal of the solids. For example, solids collected from a wastewater treatment process often include approximately 30% by weight solid contaminants from the wastewater. Currently, there is a limitation to the amount of water and/or fluids that can be removed from solids using conventional wastewater thickening and dewatering processes since a significant amount of the water and/or fluids remains trapped in the solids (e.g., in cells).
Wastewater may also include a significant amount of agricultural chemicals. The composition and quantity of chemicals produced from used agriculture and/or horticulture processes (for example, herbicides, pesticides, insecticides) may make removing the chemicals from wastewater using current wastewater processing techniques difficult. Runoff and increasing urbanization may also provide additional sources of pollution not currently controlled by wastewater treatment facilities.
The following patents and publications describe existing techniques for treating wastewater: U.S. Pat. Nos. 6,745,961 to Korstvedt; 6,685,834 to Murthy et al.; 6,635,178 to Bowman et al.; 6,402,065 to Higgins; 6,013,183 to Stephenson et al.; 5,954,964 to Nielsen et al.; 5,846,425 to Whiteman; 5,643,461 to Neff et al.; 5,232,584 to Wang et al.; 4,342,650 to Erickson et al.; and 4,159,944 to Erickson et al.; Onyeche et al. “Sludge Homogenization as a Means to Reduce Sludge Volume and Increase Energy Production,” Electron. J. Environ. Agric. Food Chem., 2003, pp. 291-296; Fairey et al. “Evaluation of Kady Biolysis System (BLS™) at the Plum Island Wastewater Treatment Plant”, Mar. 4, 2004, p. 1-16; and U.S. Office of Waste and Office of Wastewater Management “Primer for Municipal Wastewater Treatment Systems,” EPA 832-R-04-001, September 2004, all of which are incorporated by reference herein.
Many wastewater treatment facilities are undersized and/or overutilized, thus handling the volume and/or removing the chemical contaminants and processing solids in an efficient manner is difficult. Thus, there is a need for new technology that is compatible with existing wastewater treatment facilities that can remove contaminants and/or reduce the amount of solids being produced from the wastewater facility.